Smog contains particles that reflect the sun’s rays and cool Earth’s surfaceDennis MacDonald/Alamy
Cleaning up air pollution in Europe and North America could result in more weakening of the Atlantic Meridional Overturning Circulation (AMOC), an ocean current that is critical for Europe’s climate.
The smog and soot dirtying the air around the world claim some 7 million lives every year and induce illnesses that affect many others. Yet aerosols – small particles of substances like sulphur dioxide that make up most ground-level pollution – tend to reflect sunlight and brighten clouds, which wards away some of the sun’s heat.
In recent years, research has revealed how cutting air pollution from sources such as shipping has caused global temperatures to rise even faster. “As we reduce aerosols, they’re going to unmask warming,” says Michael Diamond at Florida State University.
To date, scientists’ understanding of how aerosols impact the climate has been limited to running the same kind of global simulations that are used to study the greenhouse effect. These global models have shown “if there’s an increase in aerosol, that cools the surface in the North Atlantic, which strengthens the AMOC,” says Robert Allen at University of California, Riverside, “but if you reduce global aerosol emissions, that warms the surface and weakens the AMOC.”
